Automatic telephone system



' Mar. 3, 1925.

R. G. RICHARDSON AUTOMATIC TELEPHONE; SYSflEll 'H'ndnegllfimhardsu h zFiled Jan. 19, 1 92o a Q I Mar. 3, 1925. 1,528,343

R. G.'RICHARDSON AUTOMATIC TELEPHONE SYSTEII Original ilaim. 19,1920 3sne tssneet z Man-'3, 1925; 1,528,343

R. G. RICHARDSON AUTOMATIC TELEPHONE SYSTEM,

Original Filed Ja 19. 1920 s-sha e ts snaet a [J/er Bio ck I Ha 025gfizlimhardgbn;

Patented Mar. 3, 1925.

UNITED STATES RODNEY 'e. RICHARDSON, or CHICAGO,

ILLINOIS, ASSIGNOR T0 AUTOMATIC ELECTRIC COMPANY, OLE CHICAGO, ILLINOIS,A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Application filed January 19, 1920, Serial No. 352,391.

I '0 all whom it 972 e 21 concern:

Be it known that I, RODNEY G. RIOHARD- son, a citizen of the UnitedStates of America, and a resident of Chicago, in the county of Cook andState of Illinois, have invented certain new and useful Improvements inAutomatic Telephone Systems, of which the following is a specification.

My invention relates in general to automatic telephone systems, but isconcerned more particularly with automatic party line telephone systemsin Which means is provided at the exchange for selectively signallingthe different stations on a party line; and the object of the inventionis to provide a more efficient and flexible system of this kind than hashitherto been available.

Numerous methods of selectively ringing automatic party lines have beendevised before this. A system in wide use, which is disclosed in theUnited States patent to Goodrum, No. 1,156,475, involves the provisionof different frequencies of ringing current at the exchange and tunedbells at the subscribers stations. Each party line is accessible to aplurality of groups of connectors, the connectors of each group beingadapted to use a different frequency of ringing current to signal on acalled line. The group of connectors used in any case, and therefore thestation signalled, is determined by the number called. Other systems,employing so called frequency selecting connectors, have been devised,in which but a single group of connectors has access to any given line,each connector of the group being provided with means responsive to adigit in the called number for selecting the proper frequency of ringingcurrent.

In all these systems, the stations on each party line are definitely andpermanently associated with a particular series of call numbers, andthere is no practicable or feasible way by which the individual callnumbers maybe variably associated with the. different party linestations. Efforts have been made in the past to remedy the inherentdefects in these rigid grouping systems by employing an intermediatedistributing frame for connecting up the party lines, and withconsiderable success. The

Renewed July 14, .1924.

application of Owens, et al, Serial N0.143,- 657, filed Jan. 22, 1917,and my pending application, Serial No. 177,653, filed June 29, 1917,disclose improved selective ringing systems in which each party line isaccessible for purposes of being called by way of as many branches asthere are stations on the line, and an intermediate dis- 'tributingframe is provided at which each party line may be connected at will todesired plurality of said branches, which any branch may be shifted atwill to any party line. Means is thus provided whereby a subscriber maybe changed to another party line without changing his call number; andthese systems also effect an economy in the central office switchingmechanism by eliminating dead numbers and by permitting the load to bedistributed more advantageously.

The fact remains, however, that even in these latter systems a givencall number, while it may be changed from one party line to another, isnevertheless permanently associated with a certain particular frequencyof ringing current and therefore one of the most desirable ends, thatofutilizing the outside cable plantt-o its full capacity, is notattained. For example, in changing a subscriber from one party line toanother, he must necessarily be connected to a line on which a vacancyexists corresponding to the frequency of his call num ber, and if thereis no such vacancy in that locality, a new line must be started, eventhough there may be many lines having vacancies which correspond toother frequencies. It follows that in a working telephone system of thischaracter there will be numerous party lines which are not filled tofull capacity, and the consequent ineflicient utilization of the cableplant is a serious defect.

My invention overcomes all these objections, and provides a selectiveringing system which not only is a considerable improvement on priorsystems when considered any simply as a selective ringing system alone;but which has all the advantages of the sys tems referred to previously,with the additional advantage that it permits all vacancies on partylines to be filled up without regard to frequencies, and thus securesfull and at economy in the use of the cable plant. I accomplish theseresults by the use of an in termediate distributing frame and fre quencyselecting connectors in which, however, the various frequencies are notpermanently associated with particular call numbers. On the contrary,the relation between the frequencies and call numbers may be varied atwill and is determined by the manner in which the called line branchesare connected at the intermediate distributing frame. In calling a partyline number, the desired frequency is not selected by any particulardigit in the number, but by the entire number as a unit and the actualphysical selection does not take place until after the connector hasbeen operated, when the proper frequency of ringing current isautomatically selected andaconnected to the called line. As stated, thecall numbers are not permanently associated with particular frequencies,but any call number may be associated with any frequency; and thefrequency of the ringer of any station on a arty line may be changedwithout changthe call number.

Having stated in more or less general terms the object and scope of theinvention, the apparatus and circuits used to carry out the same willnow be explained more in detail, referencebeing had to the accompanyingdrawings, comprising Figs. 1, 2 and 3, which are circuit diagramsshowing the essential features of a telephone system embodying theinvention.

Referring to the drawings. the substation A, Fig. 1, is an ordinaryautomatic substation, which, although shown for convenience as beingindividual to the line, may equally well be a party line substation. Itcomprises the usual talking equipment and ringer, and also a callingdevice indicated by the reference character S, through the medium ofwhich the subscriber controls the central oflice switches.

The line conductors 11 and 12 extend to the exchange where theyterminate in the rotary line switch O in a manner more clearly shown inFig. 3 in the case of a called line. The line switch C may be brieflydescribed as a rotary line switch whose movable terminals or wipers haveno normal position and which have movement in a forward direction only.The construction of a line switch of this type is well known in the art.A plurality of these individual line switches may be given access to agroup of trunk lines extending to first selector switches. One of thetrunk lines to which the line switch has access is shown in the drawingsas extended to the first selector D, which is a vertical and rotaryselector switch of the usual construction. The selector D, together witha plurality of similar selectors, has access to a plurality of groups oftrunk lines, the trunk lines of each group terminating in a group ofconnector switches. One of the trunk lines to which the selector D hasaccess is shown extending to the connector E, Fig. 2. The connector Elikewise is a Vertical and rotary switch of well known construction,and, except for the circuits having to do with the selective ringing, isof the usual type which is in common use. It is understood that secondand third selectors may be used if desired according to the capacity ofthe exchange; and it may be stated that the system of trunking employedis the same as the system commonly referred to as the percentagetrunking system.

in Fig. 3 I have shown in detail the manner in which a party line isconnected for both incoming and outgoing service at the main andintermediate distributing frames. The layout shown may be describedbriefly as follows: The four party line comprising conductors 201 and202, which has the four substations A to A inclusive, connected inbridge thereof, is assumed to enter the exchange by way of cable pair Bwhich is terminated on the cable side of the main distributing frame inthe usual manner. This cable pair is connected by means of a jumper withany desired pair on the switchboard side of the main distributing frame,as for example, pair 1. All the terminal sets on the switchboard side ofthe main frame are connected by means of-cables with correspondinglynumbered terminal sets on the vertical side of the intermediatedistributing frame. The line switch cables which extend to theindividual line switches are connected in multiple with these cables andmay be terminated on the switchboard side of the main distributing frameas shown, or on the vertical side of the intermediate distributingframe, it is immaterial which. The jumper on the main distributing framehaving been run it will be evident that the party line shown will beconnected for outgoing service by way of the individual line switch O,which has access to a plurality of first selectors similar to the firstselector D. The line is connected for incoming service at theintermediate distributing frame. On the horizontal side of this frameare terminated the normal cables coming from all the connector groups inthe exchange. These cable pairs are preferably arranged in consecutiveorder on the horizontal side of the frame inaccordance with the callnumbers, and the terminal sets should be so numbered. This is shownclearly in the drawing wherein the first set of bank contacts in each ofthe first four levels of the connector E are connected by conductorswith terminal sets 111, 121, 131 and 141, respectively. There is alsoprovided on the vertical side of the intermediate frame a series l Oilof so called idler blocks, the terminal sets on which are arranged ingroups of five each, each group being wired as shown in the drawing. Theupper set in each group is preferably numbered in accordance with thenumber of the group according to any desired numbering scheme, while theother four sets of each group are preferably marked in accordance withthe tour ditlerent frequencies of ringing current. The manner ofconnecting the line for incoming service will now be apparent. Terminalset 1 on the vertical side of the intermediate frame is connected bymeans 01"? the triplex juniper 204 with the upper terminal set of somevacant group on the idler blocks, group 1, for instance. Then the othertour terminal sets oi the group are connected by means of jumpers 205,206, 207, and 208 with the terminal sets on the horizontal side of theintermediate frame which correspond to the call numbers which have beenassigned to the different stations on the party line. It is to beclearly understood that any call numbers whatever may be used. The lineis now completely connected for both incoming and outgoing service.

I will now describe the operation of the circuits involved with thespecial object of explaining the method by which the stations on a lineare selectively signaled. For this purpose it will first be assumed thatthe subscriber at substation A desires to call the subscriber atsubstation A, whose ringer will be assumed to be tuned to the 16-cyclefrequency, and whose telephone number, therefore, when the line isconnected as shown in the drawing, will be 111. When the receiver isremoved from the hook at substation A, a circuit is completed over theline conductors 11 and 12 for the line relay 14 of the line switch C.Upon energizing, the line relay completes a circuitextending through theswitching relay 13 and the stepping magnet 15 in series at its armature20, and at its armature 19 connects the test wiper 26 to the abovecircuit at a point midway between the switching relay and the saidstepping magnet. The operation now depends upon whether the test contactwith which the test wiper 26 is in engagement is busy or is not busy, Ifthis test contact is busy it will have a ground potential upon it, theswitching relay 13 will be short circuited, and the stepping magnet 15,which interrupts its own circuit, will be operated as a buzzer toadvance the switch wipers 27, inclusive, step by step in search of anidle trunk line. This operation will continue as long as the test wiper26 engages grounded or busy test contacts. However, we may assume thatin the present case when the call is initiated, the selector D is idleand the test contact 31 therefore is not grounded. Under thesecircu1nstances, when the line relay 1th is energized. the switchingrelay 13 is energized immediately afterwardswith the result that theline conductors 11 and 12 are disconnected from the winding of the linerelay 14 and from ground, respectively, and are extended by means ofarmatures 16 and 18, wipers 25 and 2?, bank contacts and 32, andarmatures 63 and and their resting contacts to the upper and lowerwindings ot the line relay 50 of selector D.

Immediately upon the extension of the line above described the linerelay 50 will be energized over the line circuit and will close thecircuit of the slow acting release relay 51. Upon energizing, relay 51prepares the circuits of the selector for the vertical operation in theusual manner, and at armature 58 completes a holding circuit extendingback to the line switch C over the following path: ground at G workingcontact of armature 58 and the said armature, conductor 90, test contact31, test Wiper 26, armature 17 and its working contact, winding of theswitching relay 13, and the winding of the stepping magnet 15 tobattery.

acting relay 52 and the vertical magnet 56 in series to battery. By theoperation of the vertical magnet the selector shaft is raised step bystep until the wipers -72, inclusive, stand opposite the desired levelof bank contacts. The slow acting relay 52 is energized in series withthe vertical magnet, retaining its armature attracted throughout thevertical movement, of the switch, and upon the closure of the verticaloff normal springs 62 completesa circuit for the ste ping relay 53. Uponenergizing, relay 53 prepares a circuit for the rotary magnet 54 atarmature 60, and at armature 61 establishes a locking circuit foritself. At the end of the vertical operation of the switch theslow-acting relay 52 is deenergized and closes the circuit of the rotarymagnet, which is thereupon energized to advance the wipers 70-72,inclusive, into engagement with the first set of bank contacts in thelevel opposite which they were raised. The rotary magnet also breaks thecircuit of the stepping relay 53, which accordingly is deenergized tobreak the circuit of the rotary magnet, which thereupon deenergizes alsoand again closes its interrupter contact.

it is understood that the above circuit is The operation now dependsupon whether. the test contact with which the test wiper 71 is inengagement is or is' not busy. If thistest contact is busy it will havea ground potential upon it, and the stepping relay 53 will be energizedagain over a circuit which extends from the grounded test contact, byway of the test wiper 71, armature 64 and its resting contact, theinterrupter contact of the rotary magnet, the off normal springs 62, andthe winding of the stepping relay 53 to battery. The stepping relay willtherefore again close the circuit of the rotary magnet 54, which willoperate to advance the-switch wipers into engagement with the nextvsetof bank contacts. This operation by which the stepping relay and therotary magnet are alternately energized and deenergized will continue aslong as the test wiper 71 engages busy or grounded test contacts. In thepresent case it will be assumed that the trunk line shown in thedrawings. is the first idle trunk line, and when, therefore, the testwiper 71 arrives at test contact 74 and the rotary magnet, isdeenergized, the stepping relay 53 will not again be energized; butinstead the switching relay 55, which hitherto hasbeen short circuited,will be operated by current flowing over the following path:

Grounded conductor 90, winding of the switching relay 55, interruptercontact of the rotary magnet, 01f normal springs 62, and the winding ofthe stepping relay 53 to battery.

Owing to the high resistance of the switching relay 55, the steppingrelay 53 is not operated; Upon energizing, relay 55 disconnects-theincoming line conductors from the windings of the line relay 50, andextends them by way of armatures 63 and 65 and their working contacts,wipers and 72, bank contacts 73 and 75, conductors 76 and 78, andnormally closed contacts of the back bridge relay 100 to the upper andlower windings of the line relay 101. of the con.- nector E, Fig. 2.

The calling line having been extended to the connector E, the line relay101 is energized over the line circuit and completes a circuit for theslow acting release relay 102. Upon energizing, relay 102pre-pares thecircuits of the connector for operationin its vertical movement, andalso closes a holding circuit extending back: to the selector D, whichmay be traced as follows:

Ground at G working contact of arma ture 116 and said armature,conductor 77, test contact 74, test wiper 71,, and armature 6 1 and itsworking contact, to conductor 90, where it joins the previouslydescribed holding circuit extending bacl: to the line switch C.

WVhen, the calling subscriber operates his calling device in accordancewith the next contact, oli, normal springs 150 and 152,.

winding of the slow acting relay 103, and the winding of the verticalmagnet 111 to battery.

This is the circuit over which the first impulse is transn'iitted. Atthe first upward step of the switch shaft, however, the 011 normalsprings are shifted, and the circuit extends from the working contactof. armature 117 by way of off normal contact.

springs 150 and 151, armature 118 and its working conta'it (relay 103being now energized), winding of; relay 103, and the winding of thevertical magnet- 111 to bat:- te-ry. By the operation of the verticalmagnetv 111 the switch shaft is raised step: by step until the wipers 16O163, inclusive, stand opposite the desired level of bank contacts.Atthe end of'the vertical movement of the switch the slo.wacting relay103 is,

deenergized and preparestheswitch for operation, in its rotary movement.

The calling subscriber may now operate his calling device in accordancewith the last digit in' the number, thereby producing as before a seriesof interruptions in the circuit of, the line relay 101. At each. resulting deenergization the line relay now sends a current impulsethrough the rotary magnet 113 over the following. circuit:

Ground at Gf, armature 115 and its rest-- ing contact, armature 117 andits working contact, o-tf: normal springs 150 and 151, armature 118 andits resting contact, resting contact of armature 124- and the saidarmature, resting contact of armature 135 and the said armature, and thewinding of the rotary magnet 113 to battery.

In response to these impulses the rotary magnet operates to rotate thewipers 160- 163, inclusive, into engagement with the desired set of bankcontacts in the level. op.- posite which they were'raisedL Since, in thepresent case, the desired station is #111, the wipers will have beenraised opposite the first level, and they will be rotated intoengagement with the first set of contacts in this level, or contactsindicated by reference characters 171,172 and 173. The slow-acting relay106 isenergized in parallel with the rotary magnet and retains itsarmatures attracted throughout the rotary movement of the switch. Atarmature 128 relay 106 connects the test wiper 161 to the winding of thebusy test relay 105 and at its. armature 129 relay 10.6 closes a shuntaround armature 12a oil the test relay and its resting contact to guardagainst the possibility of the said test relay being momentarilyenergized while the test wiper 161 is passing over busy test contacts.It the called line is busy when the test wiper 161 arrives at the testcontact associatet therewith, as, for example, the test contact 172, thetest relay 105 will be energized, and when the slow-acting relay 106deenergizes the said relay 105 will remain locked up over a circuitwhich includes its armature 123. The test relay also opens the rotarymagnet circuit at armature 1241 in order to prevent the switch wipersbeing rotated oil the busyline accidental manipulation of the callingdial, at armatures 122 and 125 opens circuits having to do with theselective ringing which will be explained later, and at armature 126connects a lead from the busy signaling machine Q to the lower lineconductor. This operation gives the calling subscriber an audible busysignal in the usual manner and he will understand that the desired lineis for the time being inaccessible and will replace his receiver.

Let it be assumed, however, that the called line is idle when theconnector E is operated as before explained, to establish connectiontherewith. Under these circumstances when the switch wipers 160163,inclusive, are brought to rest in engagement with bank contacts 171-173,inclusive, the test relay 105 will not be energized, tor the test contact 172 will not be grounded; and when the slow-acting relay 106deenergizes, upon the cessation of the rotary movement, the followingcircuit will be completed:

Ground G at line switch C, Fig. 3, resting contact of armature 1S andthe said armature, conductor 213, conductor 21 1, and a strand of thetriplex jumper 20-1 to the lower terminal in the upper terminal set ofthe first group of idler blocks, whence the circuit continues by way 01resistance 210, the lower terminal of the 16-cycle set, a strand ofjumper 205, the lower terminal of the set numbered 111 on the horizontalside of the I. D. F, conductor 215, bank contact 173, wiper 163,armature 121, and its rest ing contact, armature 136 and its restingcontact, resting contact or armature 125 and the said armature, armature130 and its resting contact, lower winding ot relay 109 and the lowerwinding of relay 1.10 to battery.

It should be noted at this time that upon the deenergization of relay106 relay 108 is connected to the upper line wiper 160 the same way asrelay 109 is connected to the lower line wiper 163, and a branch of thecircuit traced above will extend from a point midway between relays 109and 110 by way of the lower winding of relay 108, to the upper conductorof the called line circuit, and thence by way of the line relay 14 ofline switch C, to battery. The lower windings of relays 108, 109 and 110are so proportioned, however, that the current flow over this branch isinsuflicient to operate either relay 108 or the line relay of the lineswitch C. The lower windings 0t relays 108 and 109 may be of 500 ohmsresistance each, while the lower winding of relay 110 may be of 100ohms, and with these values, it the line relay has a resistance of 500ohms, less than one tenth of the total current will flow over the branchcircuit. Ordinarily this will cause no trouble and the circuitarrangement shown is one which I prefer. However, in case the linerelays in any particular system are extremely sensitive, relay 110 ofthe connector may have .two lower windings instead of one, and thusentirely separate the circuits of relays 108 and 109. To continue withthe operation, when the circuit is closed through the lower windings oftrelays 109 and 110 in series, relay 109 is energized, but relay 110,being a marginal relay, does not energize on account of the resistance210 which is included in the circuit, and which may have a value ofabout 1000 ohms. Upon energizing, relay 109 establishes a lockingcircuit for itself at its armature 1 17, connects up the 16-cycleringcurrent generator at its armature 143, closes a contact in thecircuit of the ring cut oil relay 104 at armature 141, and at armaturecompletes a circuit for the switching relay 107 as follows:

Ground at G armature 116 and its right hand working contact, conductor159, armature 142 and its working contact, upper winding of relay 107,test wiper 161, test contact 172, conductor 216, middle terminal ofterminal set numbered 111, strand of jumper 205, middle terminal of the16-cycle terminal set on the idler block, middle terminal of theterminal set numbered 1 onthe vertical side of the 1. D. F., conductor217, conductor 218, winding of switching relay 3 and the winding of thesteppingmagnet 15 to battery.

Upon the closure of the above circuit relay 107 of the connector and theswitching relay 13 of the line switch C are energized in series, thelatter relay being operated only about half way, due to the fact thatthe line relay 11 is not energized, with the result that the conductors213 and 219 are disconnected from ground G and from the line relay 1 1',respectively. When the relay 107 at the connector energizes, it opensthe r0- tary magnet circuit at its armature 135, establishes a lockingcircuit for itself at its armature 134-, connects the grounded conductor159 to the test wiper 16.1 at armature 188, and closes the ringingcircuit at armatures 182 and 136, relays 108 and 109 being disconnectedfrom the line wipers at the resting contacts of these two latterarmatures. The ringing circuit over which alternating current from the16-cycle generator flows out over the lower line conductor, throughbridged ringers at the four substations in parallel, and back over theupper line conductor and through the upper winding of the ring cut offrelay 104, is the usual ringing circuit, and since it is well understoodit will not be traced out in detail. The

ringer at substation A which is tuned to the in operated position shortcircuits the resistance 210, thereby cutting the said resistance out ofthe line circuit.

When the called subscriber at substation A. removes his receiver inresponse to the ringing of his bell, the cut off relay 104: isenergized, either by current trom the gen orator or by direct current:t'rom the battery associated therewith, and upon attracting itsarmature 120 establishes a locking circuit for itself by way of itslower winding. Relay 10a also disconnects is upper winding and theringing current generator at armatures 119 and 12.1 and at the workingcontacts of the same armatures completes the talking circuit byconnecting'the incoming line circuit with the line wipers 160 and 163.The transmitter at the called station is now supplied with currentthrough the windings ot the double wound back bridge relay 1.00 in theusual manner. Upon energizing, relay 100 reverses the direction ofcurrent tlow in the calling line, as is the usual custom for the purposeof operating a meter or supervisory mechanism, although no such devicesare shown in the present system.

The desired connection has now been established and the subscribers mayconverse as desired. The complete talking circuit is shown in heavylines, and, being of the usual character, will not be traced in detail.

lVheu the conversation is finished both subscribers will replace theirreceivers. VJhen the receiver is replaced at substation A the line relay101 of the connector is deenergized, followed by the deenergization ofthe slow-acting release relay 102. Relay 10:2 closes the circuit of therelease magnet 112 through the medium of which the con nector E isrestored to normal in the usual manner. Belay 102 also breaks theholding circuit extending back to the selector D the selector and lineswitch to normal position also. It should be noted that when the relay102 of the connector is deenergized the locking circuit of relay 109 isbroken, while the locking circuit of the switching relay 107 is notbroken until the connector switch has completely returned to normalposition. The locking circuits are arranged in this way so that the linewipers of the connector will be disconnected while they are rotatingback over the bank contacts during the release of the switch.

A brief explanation will now be given of the operation of selectivelysignaling the other stations on the party line. Suppose that the stationA is called, the ringer at this station being turned to the i li'l-cycleringing current, and the telephone nun'iher assigned. being #121. Theoperation oi? the switches is the same as has already been describedexcept that since the number called is #121, the connector E willestablish connection with the called line by way of bani; contacts 17%,175 and 170. the terminal set on the horizontal side of the l. D. F.which is numbered 121, jumper t 'lltl, and the il -cycle idler blockterminal 501'. it the end of the rotary operation of the switch, whenthe slow-acting relay 106 decneigizes, a circuit is completed tor therelays 109 and 110, which is the same cir cult as was described in theprevious case, except that it does not include the resistance 210. Itfollows that since the resist ance 210 is not included in the circuit,the marginal relay 1.10 at the connector will be energized at the sametime that relay .09 is energized. Relay 110 establishes a locking circunfor itself at its armature 144, and at its armature 14:6 connects up the33-cycle ringing" current generator. it will be evident, then. thatduring the signaling operation 33-cycle ringing current will betransmitted over the called line to actuate the 33-cycle ringer atsubstation A.

The ringers at substations A and i-r are adapted to respond to ringingcurrent o! 50 and 66 cycles, respectively. It will be observed thatthere is a reversal in the line connections at the idler blocl-z betweenthe 33 and 50 cycle terminal sets, and it tollows that either telephonenumber 131 or 1 1 is called the normally grounded side Oil the calledline will be connected with by the upper wiper 160 of the connector E,instead of by the lower wiper 163. This causes relay 108 of theconnector to become cl'lective to connect up either 50 or ($6 cyclegenerator depending upon whether the relay 110 does or does notenergize. The energizetion of this relay, ot' course, depends on whetherresistance 210 is or is not included. in the circuit, the same as waspreviously explained,

From the foregoing considerations it will lill) be clear that theselective'ringing iscontrolled entirely by the connections at the idlerblock and it will be evident that any telephone number may be caused toring on any desired frequency simply by connecting the jumper to theappropriate idler block terminal. This makes it possible tochangesubscribers from one party line to another, and change the ringingfrequency of their telephones, if necessary, without changing theirtelephone numbers.

The selective ringing system herein disclosed may be used for two-partyline service if desired. The four-party selective ringing control systemis a combination of a line reversal and a resistance system, and it willbe obvious that either system may be used separately to controltwo-party selective ringing. Suppose that it is desired to have twopartyselective ringing controlled by the reversal of the conductors of thecalled line. In this case it would be only necessary to omit the relayllOat the connector If] and the resistance 210 and the relay 2124 at theidler block. Since the line is to be a twoparty line, only three sets ofterminals would be used in each idle block group, the ones omitted beingthe terminal sets which, in the present disclosure, are used for 16 and50 cycle ringing. In case it is desired to use the resistance method ofcontrol. the resistance 210, and relay 212 are retained, together withthe terminal sets used for the 16 and 50 cycle ringing; while at the connector the relay 108 may be omitted. any desired ringing currentfrequencies may be used for the two-party service, and the modifications proposed are not restricted in any way to the frequenciesmentioned.

The private or individual lines may be connected up also along with theparty lines, and this is in fact advisable in order to distributetrafiic evenly. among the different connector groups. In connecting upan individual line no idler block group of terminal sets is used, butthe jumper is run directly from the terminal set on the hori- Zontalside of the I. D. F. corresponding to the call; number assigned to theterminal set on the vertical side of the I. D. F. which has been crossconnected at the main. dis tributing frame.

I am aware that changes maybe made in the system herein disclosedwithout departing from the general principles of the invention, and onthat account I do not wish to be restricted to the precise forms andmodifications herein described; but desire to secure and have protectedby Letters Patentall forms of my invention which may hereafter bedevised, limited only by the scope of the appended claims:

What I claim is:

1. In an automatic party line telephone system, a frequency selectingconnector switch for completing connections to called party lines,frequency selecting mechanism in said switch comprising a plurality ofrelays, and circuit arrangements whereby said mechanism is controlled inits selecting operations exclusively over talking conductors of calledlines.

2. In an automatic party line telephone system, a frequency selectingconnector switch for completing connections to called party lines,frequency selecting mechanism in said switch, and circuits includingtalking conductors of said called lines for controlling said mechanism.

3. In an automatic party line telephone system, a connector switch forcompleting connections to four party telephone lines, a plurality ofbranches for each line over which connection thereto may be completed,and frequency selecting relays in said switch controllable over theparticular branch of a called line by which connection thereto iscompleted, for selecting any one of four different ringing currentfrequencies.

i. In an automatic party line telephone system, a connector switch forcompleting connect-ions to called party lines, a plurality of branchesfor each line over which connection thereto may be completed, andfrequency selecting relays in said switch controllable over a talkingconductor of the particular branch of a called line by which connectionthereto is completed.

In an automatic party line telephone system, a connector switch forcompleting connections to called party lines, a plurality of branchesfor each line over which con nection thereto may be completed, and afrequency selecting mechanism in said switch comprising marginal andnon-marginal relays controllable over the particular branch of a calledline by which connection thereto is completed.

6. In a telephone system, a party line, a connector switch havingmovable line terminals, a plurality of branches of said line accessibleto saidterminals, a pair of ringing current selecting relays in saidswitch, means for operating said switch to connect said terminals withany one of said branches, means for thereafter connecting said relays tothe said terminals, respectively, and means establishing characteristicelectrical conditions in said branches effective to operate said relaysselectively.

7. In a telephone system, a' party line, a connector switch havingmovable line terminals, a plurality of branches of said line accessibleto said terminals, a pair of ringing current selecting relays in saidswitch, means for operating said switch to connect said terminals withany one of said branches, means for thereafter connecting said relays tothe said term1nals,'respectively, means establishing characteristicelectrical conditions in said branches effective to operate said relaysselectively, another relay for disconnecting both relays of said pair,and a circuit for said other relay closed by whichever relay of saidpair that is operated.

8. In a telephone system, aparty line, an automatic connector switch, aplurality of branches of said line accessible to said switch, means foroperating said switch to connect a calling line with any one of saidbranches, and selective ringing equipment in said connector selectivelycontrolled over a talking conductor of the connected branch toselectively signal a desired station on said line.

9. In a telephone system, a tour party .line, an automatic connectorswitch, a plurality of branches of said line accessible to said switch,means for operating said switch to connect a calling line with any oneof said branches, four ringing current generators of differentelectrical character corresponding to the four stations on said line,and selective mechanism in said connector selectively controlled overthe connected branch to select the proper generator to selectivelysignal a desired station on said line.

10. In a telephone system, a four party line, an automatic connectorswitch, a plurality'of branches of said line accessible to said switch,means for operating said switch to connect a calling line with any oneof said branches, four ringing current generators of diiierent frequencycorresponding to the four stations on said line, and selective mechanismin said connector selectively controlled over the connected branch toselect the proper generator to selectively signal a desired station onsaid line.

11. In a telephone system, a party line, an automatic connector switch,a plurality of branches of said line accessible to said switch, meansfor operating said switch to connect a calling line with any one of saidbranches, and self-locking relays in said switch selectively controlledover a talking conductor of the connected branch to selectively signal adesired station on said line.

12. In a telephone system, a party line, an automatic connector switch,a plurality of branches of said line accessible to said switch, meansfor operating said switch to connect with any one of said branches,ringing current generators of different electrical character, andmechanism individual to said connector selectively controlled over atalking conductor of the connected branch to select the proper generatorto selectively signal a desired station on said line.

13. In a telephone system, a party line, an automatic connector switch,a plurality of branches of said line accessible to said switch, meansfor operating said switch to connect with any one of said branches,ringing current generators of different frequency, and mechanismindividual to said connector selectively controlled over a talkingconductor of the connected branch to select the proper generator toselectively signal a desired station on said line.

14. In a telephone system, a party line, an automatic connector switch,a plurality of branches of said line accessible to said switch, meansfor operating said switch to connect with any one of said branches, andrelays in said switch selectively controlled over a talking conductor ofthe connected branch to selectively signal a desired station on saidline.

15. In a telephone system, a calling and a called party line, anautomatic connector switch, a plurality of branches of the called lineaccessible to said switch, means whereby a subscriber on the callingline can operate said switch to connect his line with any one oi saidbranches, and selective ringing equipment individual to said connectorselectively controlled over a talking conductor of the connected branchto selectively signal a desired station on the called line.

16. In a telephone system, a calling and a called party line, anautomatic connector switch, a plurality of branches of the called lineaccessible to said switch, means whereby a subscriber on the callingline can operate said switch to connect his line with any one of saidbranches, ringing current generators of different electrical character,and mechanism individual to said connector selectively controlled over atalking conductor of the connected branch to select the proper generatorto selectively signal a desired station on the called line.

17. In a telephone system, a calling and a called party line, anautomatic connector switch, a plurality of branches of the called lineaccessible to said switch, means whereby a subscriber on the callingline can operate said switch to connect his line with any one of saidbranches, ringing current generators of different frequency, andmechanism individual to said connector selectively controlled over atalking conductor of the connected branch to select the proper generatorto selectively signal a desired station on the called line.

18. In a telephone system, a calling and a called party line, anautomatic connector switch, a plurality of branches of the called lineaccessible to said switch, means whereby a subscriber on the callingline can operate said switch to connect his line with any one of saidbranches, and relays in said switch selectively controlled over atalking conductor of the connected branch to selectively signal adesired station on the called line.

19. In a telephone-system, a party line having two branches, a connectorswitch and means for operating the same to connect with either of saidbranches, and a pair of ringing current selecting relays in said switchcontrollable over said branches, re spectively.

20. I11 a telephone system, a party line having two branches, aconnector switch and means for operating-the same to connect with eitherof said branches, a pair of ringing current selector relays in saidswitch, and a normal connection from one side of said line to ground foroperating said relays, there being a reversal in the line conductors ofone of said branches, whereby each relay is operated only when aparticular branch is connected with.

21. In a telephone system, a party line having two branches, aconnectorswitch and means for operating the same to connect with either of saidbranches, a resistance in a talking conductor of one of said branches,and a marginal ringing current selecting relay in said connector notoperable over the talking conductor of the branch containing saidresistance but operable over a talking conductor of the other branch.

22. In a telephone system, a party line, frequency selecting connectorswitches, and a plurality of branches of said line accessi ble to saidswitches, one of said branches having itsline conductors reversed forcontrolling the frequency selection.

28. In a telephone system, a party line, frequency selecting connectorswitches, a plurality of branches of said line accessible to saidswitches, and a resistance in one of the talking conductors of one ofsaid branches for controlling the frequency selection.

24. In a telephone system, a party line, frequency selecting connectorswitches, a plurality of branches of said line accessible to saidswitches, two of said branches having their line conductors reversed,and a resistance in a line conductor of a reversed branch and also in aconductor of a non-reversed branch, the said reversals and resistancebeing effective to control the frequency selection in any connectorwhich is operated to connect with said line. 1

2-5. In a telephone system, a party line, frequency selecting connectorswitches, a plurality of branches ofsaid line accessible to saidswitches, a resistance in one of the line conductors of one of saidbranches for controlling the frequency selection, and means forshort-circuiting said resistance after the frequency selecting operationis completed.

26. In a telephone system, a party line, frequency selecting connectorswitches, a plurality of branches of said line accessible to saidswitches, each branch comprising talking conductors and. a thirdconductor local to the exchange, a resistance in one of the lineconductors of one of said branches for controlling the frequencyselection, and a relay energized over the third conductor of said branchfor short-circuiting said resistance. 1

27. In a telephone system, a party line, connections normally existingfrom the two talking conductors of said line to the opposite poles orthe exchange battery, respectively, a plurality ofbranches of said line,a connector switch operable to connect with said line via any one ofsaid branches, and ringing current selecting relays in said switchcontrolled by current flow from said battery over a talking conductor ofthe branch by which the connection is estab lished.

28. In a telephone system, a party line, connections normally existingfrom the two talking conductors of said line to the opposite poles oftheexchange battery, respec tively, a plurality of branches of saidline, a connector switch operable to connect with said line via any oneof said branches, one of said branches having a reversal in its talkingconductors, and ringing current selecting relays in said switchcontrolled by current flow from said battery over a talking conductorof'the branch by which the connection is established. 7

29. In a telephone system, a party line, connections normally existingfrom the two conductors of said line to the opposite poles of theexchange battery, respectively, a plurality of branches of said line, aconnector switch operable to connect with said line via any one of saidbranches, two of said branches having reversals in their talkingconductors, a resistance included in a line conductor of one of thereversed branches and also in a line conductor of one of the brancheswhich is not reversed, and ringing current selecting relays in saidswitch controlled by current flow from said battery over the branch bywhich the connection is established.

30. In a telephone system, a party line,

connections normally existing from the two 1 conductors of said line tothe opposite poles of the exchange battery, respectively, a plu ralityof branches of said line, a connector switch operable to connect withsaid line via any one of said branches, a resistance in one of thetalking conductors of one of said branches, and a ringing currentselecting relay in said switch controlled by current flow from saidbattery over a talking conductor of the branch by which the connectionis established.

81. In a telephone system, party lines, groups of automatic connectorswitches, a separate series of party line branches accossible to theswitches in each of said groups,

means for variably connecting each party hne with any desired plurahty0t said branches, and ringing mechanism in each groups oi automaticconnector switches, a.

separate series of party line branches accessible to the switches ineach of said groups, means for variably connecting each party line withany desired plurality of said branches, and ringing mechanism in eachconnector switch selectively controllable over a talking conductor ofany branch with whichconnection is established.

In a telephone system, party lines, groups of automatic connectorswitches, a series of party line branches accessible to each group ofconne tors, a distributing frame whereat each pa line is connectedindiscriminately with any plurality of said branches, and ringingmechanism in each connector selectively controllable over any branchwith which connection is established.

34-. In a telephone system, party lines, automatic connector switches, aseries of party line branches accessible to said connectors, adistributing frame whereat each party line is connected with a pluralityof said branches, and ringing mechanism in each connector selectivelycontrollable over a talking conductor of any branch with whichconnection is-established.

In a telephone system, a party telephone line incoming to the exchange,a calling branch for said line terminating in an automatic switch, asmany called line branches for said line as there are stations on theline, connector switches having access to said called line branches,means in each connector controllable over talking conductors of theseveral called line branches of said party line for selectivelysignaling any station thereon, and a distributing frame on which thesaid line and its called line branches are connected by means ofjumpers.

36. In an automatic party line telephone system, a connector switch forcompleting connections to called party-lines, a plurality of branchesfor each line over which connection thereto may be completed, fre quencyselecting relays in said switch controllable over a talking conductor ofthe particular branch of a called line by which connection thereto iscompleted, and an intermediate distributing frame whereat each partyline and its several branches are temporarily connected by means ofjumpers.

37. In a telephone system, a party line, an automatic connector switch,a plurality of branches of said line accessible to said switch, meansfor operating said switch to connect with any one of said branches,selective ringing equipment in said connector selectively controlledover a talking conductor of the connected branch to selectively signal adesired station on said line, and an intermediate distributing framewhereat the said line and its branches are temporarily connected bymeans of jumpers.

38. In a telephone system, a party line, an automatic connector switch,a plurality of branches of said line accessible to said switch, meansfor operating said switch to connect with any one of said branches,ringing current generators of different frequency, mechanism in saidconnector selectively controlled over a talking conductor of theconnected branch to select the proper generator to selectively signal adesired station on said line, and an intermediate distributing 't'ranlewhere-at the said line audits branches are temporarily connected bymeans of jumpers.

89. In a telephone system, a party line having two branches, a connectorswitch and means "for operating the same to connect with either of saidbranches, a pair of ringing current selecting relays in said switchcontrollable over said branches, respectively, andv an intermediatedistributing frame whereat the said line and its branches aretemporarily connected by means of jumpers.

4:0. In a telephone system, a party line, frequency selecting connectorswitches, a plurality of branches of said line accessible to saidswitches, one of said branches having a reversal in its line conductorsfor controlling the frequency selection, and an intermediatedistributing frame whereat the said line and its branches aretemporarily connected by means of jumpers.

41. In a telephone system, a party line, frequency selectingconnectorswitches, a plurality of branches of said lineaccessible to saidswitches, a resistance in one of the talking conductors of one of saidbranches for controlling the frequency selection, and an intermediatedistributing frame whereat the said line and its branches aretemporarily connected bymeans of jumpers.

42. In a party line telephone system, an intermediate distributingframe, connector banks and party lines connected to terminal sets onopposite sides of said frame, other terminal sets on said frame arrangedin groups of fire, a jumper running from one termina set of each groupto one of said party line terminal sets, four jumpers running from theremaining sets ot each group to four connector bank terminal sets, andpermanent multiple connections between the five terminal sets of each ofsaid groups.

cs. In a party line telephone system, an intermediate distributingframe, connector banks and party lines connected to terminal terminalsets, other jumpers connecting theremaining terminal sets of each groupwith a plurality of connector bank terminal sets, and multiple lineconnections between the terminal sets of each of said groups, therebeing a reversal in the multiple connections between two sets of eachgroup.

n. In a party line telephone system, an intermediate distributing frame,connector banks and party lines connected to terminal sets on oppositesides of said frame, other terminal sets on said frame divided intogroups, a jumper connecting one terminal set of each group with one ofsaid party line terminal sets, other jumpers connecting the remainingterminal sets of each group with a pluralityv of connector bank terminasets, multiple line connections between the terminal sets of each ofsaid groups, and a resistance included in one of said multiple lineconnections between two sets of each group.

45. In an automatic telephone system, a plurality of four party lineseach terminating in an automatic switch, said switches being operable toextend outgoing calls from said lines, means for distributing incomingcals to the stations on said lines comprising a plurality of groups ofconnector switches and a plurality of groups of called line branchesaccessible thereto, a distributing frame whereat each party line may beconnected with any four of said called line branches, and means in eachof said connectors for selectively signalling all the different stationswhich correspond to the called line branches to which it has access.

46. In a telephone system, a subscribers line having an individual lineswitch at the exchange, one conductor of said line being normallyconnected to ground at said switch, an automatic connector switch andmeans for operating it to connect with said line as a called line, aringing relay in said connector for signalling the called subscriber, asecond relay for energizing said ring ing relay, a circuit for saidsecond relay including the said ground connection at the individualswitch of the called line, and means in the connector for closing saidcircuit when the called line is connected with.

17. In a telephone system, a subscribers line having an individual lineswitch at the exchange, one conductor of said line being normallyconnected to ground at said switch, an automatic connector switch haviuga pair of line wipers, means for operating said switch to connect saidwipers with the said line as a called line, a ringing current selectingrelay, a circuit for said relay completed when the ca led line isconnected with, said circuit including one of the said line wipers andthe ground connection at the said individual switch, a ringing relay forapplying the selected ringing current to the called line, and a circuitfor said ringing relay closed by said selecting relay.

48. In a telephone system, a subscribers line having an individual lineswitch at the exchange, one conductor of said line being normallyconnected to ground at said switch, an automatic connector switch havinga pair of line wipers, means for operating said switch to connect saidwipers with the said line as a called. line, a ringing current selectingrelay, a circuit for said relay completed when the called line isconnected with, said circuit including one of the said line wipers andthe ground connection at the said individual switch, a ringing relay forapplying the selected ringing current to the called line, a circuit forsaid ringing relay closed by said selecting relay, and circuits forlocking both the selecting relay and the ringing relay in energizedposition until the connection is released.

d9. In a telephone system, a subscribers line, an automatic connectorswitch, a pair of normal conductors connected with the two talkingconductors of said line and accessible to said switch, means foroperating said switch to connect with said line as a called line, aringing relay in said switch for signalling the called subscriber, andcircuit arrangements whereby the energization of said relay is dependentupon the continuity of one of said normal conductors.

30. In a telephone system, a subscribers line, an automatic connectorswitch, a pair of normal conductors connected with the two talkingconductors of said line and accessible to said switch, means foroperating said switch to connect with said line as a called line, arelay in said switch energized over one of said normal conductors whenthe said line is connected with, a ringing relay in said switch forsignalling the called subscriber, and a circuit for said ringing relayclosed by said first relay,

51. in a telephone system, a subscribers line, an automatic connectorswitch, a pair of normal conductors connected with the two talkingconductors of said line and accessible to said switch, means foroperating said switch to connect with said line as a called line, arelay in said switch energized over one oi said normal conductors whenthe said line is connected with, a private normal conductor for saidline, a ringing re ay in said switch for signalling the calledsubscriber, and a circuit for said ringing relay including said privatenormal conductor and contacts of said first relay.

52. In a telephone system, a subscribers line, an automatic connectorswitch, a pair of normal conductors connected with the two talkingconductors of said line and aceessi-lfe to said switch, means foroperating; said switch f0 connect with said line as am called line, aringing relay in said switch for signalling the called subscriber, asecond. relay in said switch for controlling the energization of saidringing relay, and a circuit for said second relay including one of saidnormal conductors.

Signed by me at Chicago, Illinois, this 14th day or January, 1920.

RODNEY (l. RICHARDSON.

